Further, from :
https://en.m.wikipedia.org/wiki/Dactylic_hexameter
Finally, even after accepting the various alterations admitted by Homer, some lines remain impossible to scan as they stand now, e.g. Iliad I.108 "not a good word spoken nor brought to pass":
ἐσθλὸν δ’ οὐτέ τί πω εἶπας ἔπος οὔτ’ ἐτέλεσσας
The first three feet of this line scan spondee-dactyl-spondee, but the fourth foot of -πας ἔπος has three consecutive short syllables.
These metrical inconsistencies (along with a knowledge of comparative linguistics) have led scholars to infer the presence of a lost digamma consonant in an old form of that line. In this example, the word ἔπος was originally ϝέπος in Ionian; this consonant lengthens the last syllable of the preceding εἶπας and corrects the apparent defect in the meter. This example demonstrates the oral tradition of the Homeric epics that flourished long before they were written down sometime in the 7th century BC.